Abstract

Background

Genome analyses have revealed that gene duplication in plants is rampant. Furthermore,
many of the duplicated genes seem to have been created through ancient genome-wide
duplication events. Recently, we have shown that gene loss is strikingly different
for large- and small-scale duplication events and highly biased towards the functional
class to which a gene belongs. Here, we study the expression divergence of genes that
were created during large- and small-scale gene duplication events by means of microarray
data and investigate both the influence of the origin (mode of duplication) and the
function of the duplicated genes on expression divergence.

Results

Duplicates that have been created by large-scale duplication events and that can still
be found in duplicated segments have expression patterns that are more correlated
than those that were created by small-scale duplications or those that no longer lie
in duplicated segments. Moreover, the former tend to have highly redundant or overlapping
expression patterns and are mostly expressed in the same tissues, while the latter
show asymmetric divergence. In addition, a strong bias in divergence of gene expression
was observed towards gene function and the biological process genes are involved in.

Conclusion

By using microarray expression data for Arabidopsis thaliana, we show that the mode of duplication, the function of the genes involved, and the
time since duplication play important roles in the divergence of gene expression and,
therefore, in the functional divergence of genes after duplication.